Adding a shared or role email account to Outlook
To add a shared (role) account to your main email account in Outlook, follow these steps:
1. Open Outlook and go to File, then Account Settings and choose Account Settings from the list.
2. Select your main account and click Change.
3. Click on More Settings.
4. Select the Advanced tab.
5. Press the Add button and enter the address of the mailbox you have permission to open and click OK.
6. Click OK on the dialog box behind, then Next and Finish to finish or click Apply and follow the process again to add another shared mailbox.
If you had extra mailboxes added already but now can't expand the folders in Outlook, this may be because your account was migrated from Exchange to Office 365. If so, follow the instructions above, but instead of clicking Add in Step Five, select Remove, click Apply, OK, Next and Finish, then add the mailbox again as instructed above.
How to open a shared folder or mailbox in Outlook for Mac
When Outlook for Mac connects to an Exchange Server mailbox, there are several ways to open shared folders or a shared mailbox. The best choice depends on the permissions you have to the shared folder or mailbox. Please follow the instructions on Microsoft Support's webpage.